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Old 11-26-2009, 07:13 AM   #1
kenneho
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Registered: May 2003
Location: Oslo, Norway
Distribution: Ubuntu, Red Hat Enterprise Linux
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dhcp-client get assigned a network address instead of a regular IP address


Hi.


I've been playing around with KVM on my ubuntu box, and after testing setting up a network bridge (so that my KVM guests can connect to a network) my Ubuntu box have suddenly started to get what seems to be a network address on my NIC when using DHCP.

My NIC is eth0, and when I do a "sudo /etc/init.d/networking restart", my eth0 devices is assigned an IP address like "a.b.c.0" (note that last zero). If I afterwards issue a "sudo dhclient3", the eth0 devices is assigned the correct IP-address such as "a.b.c.190".

Does anyone know why my NIC is getting assigned an network address insted of a regular IP address? I'm thinking that maybe the DHCP servers believes that my NIC is a router or something, but I don't know how to tell it otherwise.


Best regards,
kenneho
 
Old 11-26-2009, 07:35 AM   #2
Web31337
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perhaps your eth0 is configured with that static IP a.b.c.0 in /etc/network/interfaces (or where is a config placed in ubuntu, that one was taken from debian)?
sure it's assigned by DHCP?

Last edited by Web31337; 11-26-2009 at 07:37 AM.
 
Old 11-26-2009, 07:42 AM   #3
kenneho
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Registered: May 2003
Location: Oslo, Norway
Distribution: Ubuntu, Red Hat Enterprise Linux
Posts: 655

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Thanks for your reply.


My current /etc/network/interfaces looks like this:
Code:
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet dhcp
...which to me looks correct. The problem first appeared when I changed to contents to this:
Code:
auto lo
iface lo inet loopback

auto eth0
iface eth0 inet manual

auto br0
iface br0 inet dhcp
      bridge_ports eth0
      bridge_stp off
      bridge_fd 0
      bridge_maxwait 0
..and the IP configuration have been a mess ever since. I really don't understand what's causing this, and why changing the setup back to my current on doesn't fix things. I've even tried to purge and reinstall the "kvm", "bridge-utils" and "virt-manager" packages, just in case there was some setup here that caused the problems, but I can't find any hints.
 
Old 11-27-2009, 03:43 AM   #4
kenneho
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Registered: May 2003
Location: Oslo, Norway
Distribution: Ubuntu, Red Hat Enterprise Linux
Posts: 655

Original Poster
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I think I've managed to fix the problem. Seems to me like the clue was to remove the existing bridges "ifconfig <bridge> down", and then use brctl to remove them. Then I purged the libvirt0 package, and things looks better now.
 
  


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